Vibrato mechanism



Sept. 18, 1962 T. B. GIBBS nldl l' Y .MII l 3,054,319 Patented Sept. 18,1962 3,054,319 VIBRATO MECHANISM Thomas B. Gibbs, Delavan, Wis.,assignor to Gibbs Manufacturing 8: Research Corporation, a corporationof Wisconsin Filed Jan. 13, 1960, Ser. No. 2,144 Claims. (Cl. {i4-1.25)

This invention relates to a vibrato mechanism for a musical orelectronic musical instrument.

In certain musical instruments, as in an organ, it is desirable toprovide for a vibrato effect in ywhich the frequency of the tones of theinstrument are varied in frequency above and below their nominalfrequency -by a small percentage and at a low audio rate. `In pipeorgans this is accomplished -by varying the pressure of the air used tosound the pipes.

A principal object of the present invention is the provision of animproved vibrato mechanism for an electronic musical instrument, as anelectronic organ in which the tone generator or generators incorporate amoving element, the speed of which determines the frequency of thegenerated tones.

One feature of the invention is the provision of a mechanism including adrive source for the moving element, means including a driven elementfor transmitting motion from the source to the moving element, and meansfor advancing and retarding the driven element with respect to the drivemeans. Another feature is that the driving connection `between the drivesource and the driven element includes a rotatable cam, rotation ofwhich advances and retards the driven element with respect to the drivesource.

A further lfeature is that a drive disc is driven from the source and adriven disc is associated with the moving element, and means including acam interconnect the drive and driven discs together with selectivelyoperable gear means for rotating the cam to effect the advancement andretardation of the driven disc and thus the moving element, with respectto the drive disc.

Further features and advantages of the invention will readily beapparent from the following specification and from the drawings, inwhich:

lFIGURE 1 is a diagrammatic elevation of a tone generator system with avibrator mechanism embodying the invention;

FIGURE 2 is an elevation of the vibrato mechanism;

FIGURE 3 is a section taken along line 3 3 of FIG- URE 2; and

FIGURE 4 is an enlarged fragmentary section taken generally along line4-4 of FIGURE 3.

The invention will be described herein as embodied in a musicalinstrument utilizing a plurality of tone generators, twelve in number,each of which utilize a rotating element in the generation of the tonerepresenting signals. More specifically, the tone generators maybe ofthe type in which light is directed through openings in a mask plate andis scanned by a rotating disc, the resulting light variations impingingupon photocells in which electrical signals are generated correspondingwith the desired musical tones. Further details of the tone generatorsthemselves may be found in the Ziehlke application.

Turning now to the drawings, a tone generator drive system isillustrated in FIGURE 1 in which the twelve tone generators 10, one -foreach note of the scale, are mounted on the rear surface of a panel 11.Each of the generators is provided with a pulley disc, numbered 12-23,driven by endless fbelt 25. `It will be noted that each of the pulleydiscs 12-23 has a diameter different than the others, the diametersbeing selected to produce the required frequencies for the variousnotes. The tone generators are driven from a constant speed motor 26which, through `belt 27 and a driving mechanism 28 drives tone generatorpulley disc 23 and thus endless belt 25.

Referring now to *FIGURES 2 and 3, driven generator disc 23 is shownmounted on a shaft-23. A second shaft 29 is journalled in a bearing 3f)carried lby a frame 311 supported from panel 11. A drive disc 34- ismounted at one end of shaft 29, preferably closely adjacent and parallelwith driven generator pulley disc 23, and is directly coupled with motor26 through belt 27. A shaft 35 is rotatably carried in bearing 36located near the outer periphery of drive disc 34 and has aneccentrically mounted circular cam '37 at one end thereof received in arectangular opening 38 formed in driven generator pulley disc 23. Asbest seen in yFIGURE 4, the sides 38a and 38h of rectangular opening 38fit snugly with the edge surface of cam 37 so that there is no loosenessor play between drive disc 34 and driven disc 23.

A planetary gear 40 is mounted on the end of shaft 35 `opposite cam 37and meshes with sun gear 41 which is journalled on an extension of shaft29. A pair of brake arms 42 and y43 are pivotally mounted on pin 44extending outwardly from frame 31, and have braking surfaces 45 and 46,respectively, which conform with the surface 41a of the hub of sun gear41. A solenoid 47 is mounted on brake arm 42 and has an armature 47aconnected -by a link 48 with brake arm 43. Solenoid 47 may be energizedfrom any suitable source (not shown).

With brake arms 45 and 46 released, as shown in FIG- URE 2, gears 40 and41 rotate together as a single unit, shaft 35 is stationary relative todrive disc 34 and driven disc 23 rotates at the same rate as drive disc34. When solenoid 37 is actuated, brake shoes 45 and 46 engage surface41a of the hub of sun gear 41, causing it to remain stationary whileshaft 29 rotates within it. Planetary gear 40 rolls along the outside ofsun gear 41, rotating shaft 35 as drive disc 34 turns. The rotation ofshaft 35 turns cam 37 in the opening 38 of driven disc 23 advancing andretarding the driven disc relative to drive disc 34. The advancement andretardation of driven disc 23 relative to the constant speed of drivedisc 34 is imparted to endless member 25 and through it to each of thetone generators 10 varying the frequency of the generated tones aboveand below their nominal frequencies. The rate of advancement andretardation of driven disc 23 is determined *by the tooth ratios ofgears 40 and 41 and the rate of rotation of drive disc 34, and may beselected to provide the desired low audio rate of vibrato variations.

While I have shown and described certain embodiments of my invention, itis to `be understood that it iS capable of many modifications. Changestherefore, in the construction and arrangement may be made withoutdeparting from the spirit and scope of the invention as disclosed in theappended claims.

I claim:

1. In an electronic musical instrument having a tone generator with amoving element the speed of which determines the frequency of thegenerated tone, a vibrato mechanism, comprising: a drive source for saidmoving element; and means providing a driving connection between saidsource and said driven element, said means including a cam drivingconnection, rotation of said cam advancing and retarding a drivenelement with respect to said drive source. i

2. In an electronic musical instrument having a ton@ generator with amoving element the speed of which determines the frequency of thegenerated tone, a vibrato mechanism, comprising: a drive source for saidmoving element; means providing a driving connection between said sourceand said driven element, said means including a cam driving connection,rotation of said cam advancing and retarding a driven element withrespect to said drive source; and selectively operable gear meanS fordriving said cam.

3. In an electronic musical instrument having a tone generator with amoving element the speed of which determines the frequency of thegenerated tone, a vibrato mechanism, comprising: a drive source for saidmoving element; a drive disc rotated by said drive source; a driven discoperably associated with said moving element; means including a camconnecting said drive and driven discs; and gear means for rotating saidcam to advance and retard said driven disc with respect to said drivedisc.

4. In an electronic musical instrument having a tone generator with amoving element the Speed of which determines the frequency of thegenerated tone, a vibrato mechanism, comprising: a drive source for saidmoving element; a drive disc rotated by said drive source; a driven discoperably associated with said moving element; a shaft journalled in saiddrive disc; a cam on one end of said shaft and received in a slot formedin said driven disc; a planetary gear at the end of said shaft; a sungear mounted for rotation coaXially with said drive disc; and means forrestraining rotation of said sun gear, said cam being rotated by saidplanetary gear and advancing and retarding said driven disc with respectto said drive disc.

5. In an electronic musical instrument having a plurality of tonegenerators with respective driven pulley discs the speeds of whichdetermine the frequencies of the generated tones and having an endlessbelt for frictionally driving the discs, a vibrato `mechanismcomprising: a drive means, a drive pulley disc rotated by said drivemeans and positioned adjacent to and coaxial with one of the drivenpulley discs; means including a cam connecting said drive disc and saidone driven pulley disc; a sun gear rotatable with the drive pulley disc;a planetary gear meshed yWith said sun `gear and connected to said cam;and means for restraining said sun gear causing rotation of said camwith respect to said drive pulley disc, advancing and retarding the onedriven pulley `disc With respect thereto.

References Cited in the file of this patent UNITED STATES PATENTS2,746,334 Williams May 22, 1956 FOREIGN PATENTS 656,792 Great BritainSept. 5, 1951

